College of William and Mary assistant biology professor Harmony Dalgleish, left, and Sara Fitzsimmons, of the American Chestnut Foundation, study an 80-year-old American chestnut tree in Berlin that has mostly escaped the blight that made the species, “functionally extinct.”

BERLIN — Tucked out of sight near a well-traveled gravel road are scores of healthy American chestnut trees that could help scientists seeking to restore a species that was nearly wiped out by an invasive fungus.

Most of the trees in Berlin are tiny, some still growing out of the chestnuts that were buried by squirrels or other rodents after they fell from a healthy adult tree estimated to be 80 years old that is almost 3 feet across at the base.

It’s one of a handful of locations across the country where scientists are able to study chestnut trees that have grown to maturity and are dropping chestnuts every autumn, with young trees growing from those nuts — the normal reproductive route for a healthy species.

Harmony Dalgleish, an assistant biology professor at the College of William and Mary in Virginia, was in Vermont last week with Sara Fitzsimmons, the regional science coordinator for the American Chestnut Foundation, based at Penn State University.

“You can’t study this kind of thing, and you can’t study really big trees and the seed regeneration in Virginia because it just doesn’t happen,” Dalgleish said.

On Friday, they trekked to Maine, where they are studying another American chestnut stand.

There were once an estimated 4 billion American chestnut trees from Maine to Georgia. The fast-growing, rot-resistant hardwood was valued, both for the nuts and for the lumber from the trees that can grow to forest giants relatively quickly.

After the invasive blight from Asia swept the country around the turn of the 20th century, most of the full-sized trees across the range died. There are still an estimated 425 million trees, but they’re small trees that die before reaching maturity. The new trees sprout from the remains of the old ones, not from the nuts.